Linear motion variable resistance control

ABSTRACT

THE CHANNEL-SHAPED HOUSING OF A LINEAR MOTION VARIABLE RESISTANCE CONTROL IS PROVIDED WITH A CLOSED OR UNSLOTTED TOP WALL AND A DIELECTRIC BASE, TO WHICH THE RESISTANT AND CONDUCTIVE ELEMENTS ARE MOUNTED, IS DISPOSED IN THE HOUSING SO AS TO DEFINE PARALLE, ELONGATED OPENINGS BETWEEN THE HOUSING SIDEWALLS AND THE LONGITUDINAL EDGES OF THE BASE. A CARRIER BLOCK CARRYING THE BRIDGING CONTACT IS PROVIDED WITH SIDE MEMBERS WHICH EXTEND THROUGH THESE OPENINGS AND A SLIDER, GUIDED BY THE EXTERIOR OF THE HOUSING, IS OPERABLY ATTRACHED TO AT LEAST ONE OF THE CARRIER BLOCK SIDE MEMBERS.

United States Patent Inventor Charles Richard Goerg Milwaukee, Wis.

Appl. No. 876,501

Filed Nov. 13, 1969 Patented June 28, 1971 Assignee Globe-Union Inc.

Milwaukee, Wk.

LINEAR MOTION VARIABLE RESISTANCE CONTROL 8 Claims, 5 Drawing Figs.

US. Cl 338/183, 338/184 Int. Cl. H016 9/02 Field ofseal'ch 338/183,

I76, 184, 178, 179, I80, l8l, 182, 199

[56] References Cited UNITED STATES PATENTS 2,242,327 5/1941Rubenstein..... 338/183 3,412,36l [1/1968 Lovejoy et al. 338/l83XPrimary Examinerl.ewis l-l. Myers Assistant Examiner-D. A. ToneAttorneys-John Phillip Ryan, Glenn A. Buse, Donald D.

Benton and David T. Terry ABSTRACT: The channel-shaped housing of alinear motion variable resistance control is provided with a closed orunslotted top wall and a dielectric base, to which the resistant andconductive elements are mounted, is disposed in the hous-- ing so as todefine parallel, elongated openings between the housing sidewalls andthe longitudinal edges of the base. A carrier block carrying thebridging contact is provided with side members which extend throughthese openings and a slider, guided by the exterior of the housing, isoperably attached to at least one of the carrier block side members.

LINEAR MOTION VARIABLE RESISTANCE CONTROL BACKGROUND OF THE INVENTION 1Field of the Invention This invention relates to a variable resistancecontrol and, more particularly, to a variable resistance control havinga linear motion.

2. Description of the Prior Art Variable resistance controls havingresistance and conductive elements disposed in an elongated,channel-shaped housing with a slider carrying a bridging contact inwiping engagement with the resistance and conductive elements are wellknown. Variable resistance controls of this type, exemplified by U.S.Pat. Nos. 2,242,327 (Rubenstein) and 3,412,361 (Lovejoy et al.),typically are provided with an elongated, longitudinal slot in the topwall of the housing through which slider actuation means project. Insome applications, the exposure of the resistance and conductiveelements resulting from this slot is especially undesirable. Forinstance, variable resistance controls of this type have been consideredfor use on television sets for manual and/or remote operation. For suchuse, the control is mounted for ready access to operate. When sopositioned, the slot of the prior art devices permit the insertion offoreign objects into contact with the resistance and conductiveelements, thereby presenting a potential electrical shock hazard tochildren who might insert such objects through the opening. Also, theslot permits the ingress of deleterious foreign matter directly onto theresistance and conductive elements.

Various means, such as movable dust shields, have been suggested forclosing the slot in order to prevent this internal exposure. Generally,these means increase the cost and complexity of the manufacturer andassembly of the control. These means also usually increase the sliderfriction with resultant uneven operation of the device.

SUMMARY OF THE INVENTION A primary object of this invention is toprovide a simple, inexpensive linear motion variable resistance controlprotected against the direct entrance of foreign objects onto theresistance and conductive elements.

Another object of this invention is to provide such a linear motionvariable resistance control that does not have a slotted housing foraccommodation of the slider actuation means.

A further object of this invention is to provide a linear motionvariable resistance control with minimum sliding friction.

A still further object of this invention is to provide a linear motionvariable resistance control having limited rocking movement of theslider during actuation.

In accordance with this invention, the variable resistance control hasan elongated, channel-shaped housing with a closed or unslotted top walland a pair of sidewalls. A dielectric base, to which the resistance andconductive elements are mounted, is disposed inside the housing as thebottom thereof with the outside longitudinal edges of the base being inspaced relationship with the housing sidewalls so as to define parallel,elongated openings therebetween. A carrier block carrying a bridgingcontact in wiping engagement with both the resistance and conductiveelements is provided with side members which extend outwardly throughthese openings. A slider disposed about the exterior of the housing andguided thereby is operably attached to at least one of the carrier blockside members. Preferably, the carrier block, which is most preferablymade from a plastic material, is provided with a shoulder in slidingengagement with the top surface of the base and guide means in slidingengagement with the underside of the housing top wall to limit anyrocking movement when the slider is actuated, i.e., when a longitudinalforce is applied thereto. Preferably, the slider is provided with guidemeans in slidable engagement with the exterior of the housing sidewallsto further minimize binding of the control during operation.

BRIEF DESCRIPTION OF THE DRAWING taken along DESCRIPTION OF THEPREFERRED EMBODIMENT Referring to FIGS. l-5, a variable resistancecontrol constructed in accordance with this invention is illustrated.The

variable resistance control, generally designated 10, comprises anelongated, channel-shaped housing 12, formed from a single piece ofsuitable material, such as stamped metal or molded plastic, a dielectricbase 14, a slider drive 16, and a carried block 18 carrying slidingspring contacts 20. Housing 12 includes a closed or unslotted top wall22 and a pair of sidewalls 24 and 26 integral with the top wall andprojecting downward therefrom. Housing 12 is secured to base 14 by endtabs .28, extending downwardly from the end portions of sidewalls 24 and26, which are folded laterally over the base 14. Ears 30 and 32,integral with top wall 22 and extending upwardly therefrom, are providedfor attachment of control 10 to a mounting panel (not shown). These earsare insertable into slots provided in such a mounting panel and areeither folded over or twisted to secure the control 10 to the panel. Thecontrol also can be attached to the mounting panel in any otherconventional manner such as with tap screws.

Base 14 includes an elongated resistance element 34 having an overlayingstrip of carbonaceous or equivalent resistance film 36 and an elongatedconductive element 38, preferably in the form of an elongated strip ofhighly conductive material (such as a silver-plated metal) secured tothe top surface 13 of base 14. Terminals 40, 42 and 44 are electricallyconnected to resistance element 34 and conductive element 38,respectively, and are secured to the bottom surface of base 14 by rivets46. As shown in FIG. 4, rivets 46 extend through base 14 to serve thedouble function of securing the resistance element 34, conductive andterminals 40, 42 and 44 to base 14 and to electrically connect theresistance and conductive elements to their respective terminals. Otherconventional mounting means such as an adhesive, and other conventionalelectrical connecting means, such as solder, can be used for thispurpose. Although the resistance means is shown as a separate element34, it can be provided in the form of a striplike resistance film orcoating applied directly onto the top surface 13 of the dielectric base14. When base 14 is assembled into housing 12 (FIGS. 2 and 3), there areparallel, elongated openings 25 defined between longitudinal edges 14aand the interior of housing sidewalls 24 and 26 through which carrierblock side members 64 and 66 extend as described hereinafter.

Slider drive 16, configured to encompass the outer surfaces of housing12, includes an operating shank 48 to which a knob (not shown) or otheroperating means is attached, a pair of spaced vertical members 50 and52, and a pair of tangs 54 and 56 which are integral extensions ofvertical members 50 and 52, respectively. Vertical members 50 and 52include a plurality of integral protuberances or ribs 58 which slidablyengage the outer surfaces of walls 24 and 26 of housing 12. Theseprotuberances 58 act as guide means in providing minimum area of contactbetween slider drive 16 and housing 12 thereby minimizing friction asthe slider bar is operated. The friction can be further minimized byfabricating slider drive 16 from a plastic material such as polymers ofpropylene, ethylene, acetal and the like.

Carrier block 18, formed from an insulating material, preferably aplastic material, includes a top wall 60 having a plurality ofhemispherically-shaped nubs 62 integral with the upper surface thereofwhich ride in contact with the underside of top wall 22 of housing 12, apair of side members 64 and 66 integral with the top wall 60, projectingdownwardly therefrom and extending through the elongated opening 25between the longitudinal edges 14a of the base 14 and housing sidewalls24 and 26 and a plurality of nibs 68, 70 and 72 integral with the topwall60. Each side member of carrier block includes a lower flangesection 74 having a slot 76 into which tangs 74 and 76 into which tangs54 and 56 of the slider drive 16 are inserted and an integral shoulder78 which rides on the top surface 13 of base 14. Tangs 54 and 56 aredimensioned so that they are slightly larger than slots 74 to provide apress fit.

The sidewalls 24 and 26 of housing 12, the side members 50 and 52 ofcarrier block 18 and base 14 are dimensioned so that there is a minimumof clearance between the inside of the housing and the outer surface ofthe side members and between the outside edge of the base and insidesurfaces of the side members. The combined effect of the guidingengagement between protuberances 58 of slider drive 16 and outersurfaces of walls 24.and 26, between nubs 60 on carrier block 18 and theunderside of the top wall 22 of the housing 12, and between shoulders 78of carrier block 18 along with a minimum clearance between the sidemembers 64 and 66 of carrier block 18 and the longitudinal edges 14a ofbase 14 prevents any appreciable rocking of the carrier block or sliderduring actuation thereof yet insures free sliding movement. Binding orjerky motion of the slider drive is thereby precluded. As indicatedabove, carrier block 18 preferably is constructed from a plasticmaterial, such as polymers of propylene, ethylene, acetal and the like,which further minimizes the friction and insures free sliding motion.

Carrier block 18 carries a bridging contact which is in wipingengagement with both the resistance and conductive elements. Bridgingcontact 20, preferably formed from a spring metal ribbon, is attached tocarrier block by press fitting nibs 68 and 70 into apertures (not shown)in the base thereof. After installation, nibs 68 and 70 can be deformed,if desired, to insure a fixed connection. If carrier block 18 isconstructed from a plastic material, this deformation can be effected bythe'simultaneous application of heat and light pressure. Nib 72, whichis slightly longer than nibs 68 and 70, serves as a pilot to assist inthe alignment of nibs 68 and 70 with their respective apertures in thebase of the bridging contact during assembly of the bridging contactonto the carrier block. The bridging contact 20 is provided with aplurality of downwardly inclined spring fingers or tines 82, the lowerends of which slidably press against the resistance and contactelements. To assure good contact, bridging contact 20 is provided withtwo or more tines for each element.

From the above description, it can be seen that this invention providesa variable resistance control with a closed or unslotted top whichprevents the external insertion or direct ingress of foreign objectsonto the resistance and conductive elements. Also, the novel structureof the slider drive and carrier block provides a control capable of freesliding motion with a minimum of binding or jerky motion. In addition,the novel structure of the control allows simplified and inexpensivefabrication and assembly techniques.

Iclaim:

1. A linear motion variable resistance control comprising:

an elongated, channel-shaped housing having a closed top wall and a pairof sidewalls;

a dielectric base having longitudinal edges and a top surface disposedinside said housing, said longitudinal edges being in spacedrelationship with said sidewalls so as to define parallel, elongatedopenings therebetween;

a carrier disposed within said housing having side members extendingoutwardly through said openings and guided by said sidewalls and saidedges;

spaced parallel resistor and collector elements mounted on the topsurface of said base and extending lengthwise thereof; terminalsconnected to said resistance and conductive elements and said base;

a bridging contact attached to said carrier and insulated from saidhousing in wiping engagement with both of said elements; and

a slider disposed exteriorly of said housing and operably attached to atleast one of said side members.

2. The control according to claim 1 wherein the slider includes spaced,vertical portions guided by said sidewalls and connected to the sidemembers of the carrier.

3. The control according to claim 2 wherein the carrier side members areprovided with a shoulder in sliding engagement with the top surface ofthe base.

4. The control according to claim 3 wherein the carrier includes a topportion having a first guide means in sliding engagement with theinterior of the top wall of the housing which cooperate with saidflanges to limit the rocking movement of the carrier when a longitudinalforce is applied to the slider.

5. The control according to claim 4 wherein said vertical portions ofthe slider are provided with integral tangs which are press fitted intoslots provided in the side members of the carrier.

6. The control according to claim 5 wherein said vertical portions ofthe slider are provided with second guide means in sliding engagementwith the exterior of said sidewalls.

7. The control according to claim 6 wherein said first guide meanscomprise nubs integral with the top surface of said carrier.

8. The control according to claim 7 wherein said second guide meanscomprise vertical ribs integral with said vertical portion of theslider.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,588,779 Dated June 28, 1971 Inventor(s) Charles Richard GOERG It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 2, line 10, after 4-4 "of" should be in- Column 2, line 21,"carried" should be carrier-- Column 2, line 45, after "34, conductive"insert --element 38-- Column 3, line 10, delete "tangs 74 and 76 intowhich" Column 3, line 42, "light should be -slight-- Signed and sealedthis 6th dav of June 1972.

(SEAL) Attest:

EDWARD M.F'LETCHER,JR. ROBERT GOT'I'SGHALK Attesting OfficerCommissioner of Patents FORM po'wso "0459] USCOMM-DC 6037B-P59 a U 5GOVERNMENY PRINlNG OFFICE 9.9 D356]3l

